Ink jet printer having ink maintenance system controlling maintenance in accordance with the ink viscosity by use of a simple structure

摘要

An ink jet printer is provided with an ink circulation route which includes an ink jet head, an ink supply tank and an ink collection tank. A measuring unit obtains a value indicative of the flow resistance measured when ink flows from the ink supply tank to the ink collection tank through the ink jet head. A control unit is operable to select one of maintenance operations on the basis of the value indicative of measured flow resistance. When the flow resistance value is lower than a predetermined value, the control unit selects the operation of circulating ink around the ink circulation route as a maintenance operation, and the maintenance unit does not perform the maintenance operation which consumes some amount of ink. This configuration makes it possible to perform maintenance in accordance with the ink viscosity by use of a simple structure.